Publications

Issue Archive

Ultra-Miniature Lidar Scanner for Launch Range Data Collection

Tuesday, 03 January 2012

New scanning technology promises at least a 10× performance
improvement.

The most critical component in lidar is
its laser scanner, which delivers pulsed or
CW laser to target with desirable field of
view (FOV). Most existing lidars use a
rotating or oscillating mirror for scanning,
resulting in several drawbacks.

A lidar scanning technology was developed
that could achieve very high scanning
speed, with an ultra-miniature size
and much lighter weight. This technology
promises at least a 10× performance
improvement in these areas over existing
lidar scanners. Features of the proposed
ultra-miniature lidar scanner include the
ability to make the entire scanner <2 mm
in diameter; very high scanning speed
(e.g. 5–20 kHz, in contrast to several hundred
Hz in existing scanners); structure
design to meet stringent requirements on
size, weight, power, and compactness for
various applications; and the scanning
speed and FOV can be altered for obtaining
high image resolutions of targeted
areas and for diversified uses.

This technology employs a singlemode
optical fiber attached to the end
of a mini tube made of piezoelectric
material. The two-degrees-of-freedom
(DOF) piezo tube is driven at the first
mode of mechanical resonance frequency
of the fixed-free cantilevered fiber.
The gain of mechanical resonance
allows a small vibration at the tip of the
piezo tube to be amplified several hundred
times to vibrate the tip of the optical
fiber. The laser beam is delivered
through the single-mode fiber and the
vibrating fiber at high resonance frequency
(e.g., 5–20 kHz), and generates
scanning patterns with desirable FOV.

A laser beam is delivered via the single
fiber core to the target surface. The
direction of the light beam delivered by
the single fiber is controlled by two
piezoelectric drivers mounted orthogonally
on the mounting base of the single
fiber to generate a controllable motion
of the cantilevered fiber with two
degrees of freedom. With proper optics,
the directed light beam produces a
bright spot on the object surface. The
reflected light energy from this spot is
collected by multiple optical fibers
embedded into the outer housing.
These light collectors form a “fiber
ring.” The time duration between the
beginning of the laser pulse and receiving
pulse (in the case of pulse laser) or
phase difference between emitted and
received signals (in the case of CW laser)
determines the target distance, based on
time-of-flight principle.

The single-fiber core moves in an
area-fill fashion to produce laser light
spot sequentially over a target surface,
and light collectors record the timing
and brightness of these data points in a
pixel-by-pixel fashion. The signal receiver,
piezo controller, and the laser source
are all connected to the distal end via
flexible fiber/wire bundle with diameter
less than one millimeter. A control computer
is used to control the piezo driver
motion, laser timing and intensity,
returned signal processing, and 3D data
construction and visualization.

This work was done by Jason Geng of
Xigen LLC under the Small Business
Innovation Research Program for Kennedy
Space Center. KSC-13570

This Brief includes a Technical Support Package (TSP).

Ultra-Miniature Lidar Scanner for Launch Range Data Collection (reference KSC-13570) is currently available for download from the TSP library.

Question of the Week

This week's Question: This month, the Federal Aviation Administration proposed long-awaited rules on the commercial use of small drones, requiring operators to be certified, fly only during daylight, and keep their aircraft in sight. The ruling,...